What's a database made of?

First let's get some naming conventions out of the way. Databases are made of Tables.

Tables are collections of related data. You might have a 'Users' table, a 'Posts' table, an 'Activity' table etc...

Tables are made up of vertical columns or 'fields'. These are shared across each value in the table.

Here I've highlighted all of the ID values of the table. This is the

Here I've highlighted all of the Name values of the table. This is the

Here I've highlighted all of the Age values of the table. This is the

Each column in a table is made up of more than just a 'name' for that column (ID, Name, Age). It also enforces a 'type' for that column. Similar to typescript. For example ID in this table is a 'number' or 'INT'. Name is a 'string' or 'VARCHAR'. Age is a 'number' or INT.

The actual values in the table (In this case, each user) is called a 'row'. Here I've highlighted the first of two 'rows' in our table-

Because each column has a predefined 'type'- that means each row has to share that type. For example:

This is valid:

I changed one of the names. But the name is still a string.

This is NOT valid:

It isn't valid because the 'age' column can't handle multiple types (a String and a Number).